Aerotech I364FJ grain

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Eric

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I'm assembling an Aerotech I364FJ in my 38/720 case. 5 of the 6 grains are wrapped separate and are identical. The 6th unwrapped grain has one end cut flat, just like the other grains.

The other end has a slight concave edge and is coated with what appears to be epoxy.

My question is why is it not cut flat and coated. And where does that grain go in the assembly. The directions make no mention of different grains.

Thanks.0109180652.jpg0109180652a.jpg0109180653.jpg0109180711_HDR.jpg0109180711.jpg

Sent from my VS988 using Tapatalk
 
I'm assembling an Aerotech I364FJ in my 38/720 case. 5 of the 6 grains are wrapped separate and are identical. The 6th unwrapped grain has one end cut flat, just like the other grains.

The other end has a slight concave edge and is coated with what appears to be epoxy.

My question is why is it not cut flat and coated. And where does that grain go in the assembly. The directions make no mention of different grains.

Thanks.View attachment 335826View attachment 335827View attachment 335828View attachment 335829View attachment 335830

Sent from my VS988 using Tapatalk

More than likely that grain was the bottom end when AT casted the grains. The smooth surface is likely from the cap AT used. That's what the other grain surfaces would look like if AT didn't cut the grains to size.

Preston
 
Yeah, I had a similar grain in a 38mm KBA I motor about 2 years ago. Pretty sure I mentioned it to Karl at Aerotech and he confirmed what the others have said above. Wound up installing it in the bottom and it worked just fine.
 
I'm assembling an Aerotech I364FJ in my 38/720 case. 5 of the 6 grains are wrapped separate and are identical. The 6th unwrapped grain has one end cut flat, just like the other grains.

The other end has a slight concave edge and is coated with what appears to be epoxy.

My question is why is it not cut flat and coated. And where does that grain go in the assembly. The directions make no mention of different grains.

Thanks.View attachment 335826View attachment 335827View attachment 335828View attachment 335829View attachment 335830

Sent from my VS988 using Tapatalk
It is an end, doesn't matter where it goes as there is plenty of space between grains.

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When I assembled HPR AT motors, I always put the single exposed grain at the nozzle end of the motor. Having fresh propellant at the top makes for a more hassle free ignition.

I have one of these motors in my box that I never got to fly.
 
I assembled it with the exposed end grain next to the nozzle. The weather wasn't great at Snow Ranch. So I will fly it February 3rd.
 
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